none Efficacy of greenbug, Schizaphis graminum (Rondani), natural enemies was measured in grain sorghum using mechanical exclusion techniques and the paired comparison experimental approach. Environmental parameters were not significantly different between cagex excluding natural enemies and those allowing access. Greenbug densities on caged plants excluding natural enemies rapidly exceeded established economic threshold levels and killed the plants. Greenbug densities on caged plants that allowed natural enemy access remained far below threshold levels. Significant greenbug density increases on these latter plants occurred only after the grain crop reached the soft dought stage of development and was likely beyond economic damage due to greenbug. Predators were the only natural enemies present during most of the study and increased to high densities in the absence of greenbug by feeding on corn leaf aphids, Rhopalosiphum maidis (Fitch). Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Ecology; Land and freshwater zones; Nearctic region; North America; USA Hippodamia convergens; Hippodamia sinuata; Scymnus (Coccinellidae ); Syrphidae; Orius (Anthocoridae ); Chrysopa (Neuroptera ); Prey; Schizaphis graminum (Hemiptera); Prey population dynamics relations; Texas; Bushland Field Station; Hemipteran prey population dynamics Lysiphlebus testaceipes (Braconidae ); Aphelinus nigritus (Aphelinidae ); Hemipteran hosts; Schizaphis graminum; Prevalence, host population dynamics relations; Texas; Bushland Field Station; Prevalence in hemipteran hosts, host dynamics relations Schizaphis graminum (Aphidoidea); Hymenopteran parasites; Aphelinus nigritus & Lysiphlebus testaceipes; Prevalence; Aphelinus & Lysiphlebus (Hymenoptera), dynamics relations; Population dynamics; Predators; Coccinellidae (Coleoptera); Diptera & Neuroptera; Population dynamics relations; Texas; Bushland Field Station, insect predators & parasites relations